Transient Experiments on a Prototype Pump with an Atypical Open Impeller for Different Discharge Valve Openings

In order to obtain the transient characteristics of a low-speed centrifugal pump during the start-up and shutdown stages,dedicated experimental tests were conducted with eight different valve opening conditions.The Pearson correlation coefficient was used to reveal the linear correlation between variables.According to the results,the stable rotational speed decreases with increasing valve opening(rotational speed decreases from approximately 1472 to 1453 r/min),while the stable shaft power exhibits an increasing trend(shaft power increases from approximately 0.242 to 0.390 kW).The stable time and zeroing time of each parameter during start-up and shutdown processes vary,with the flow zeroing time significantly increasing with the relative flow,reaching up to 10.468 s,while the shaft power zeroing time is roughly between 1.219 and 1.375 s.The results demonstrate that with increasing valve opening,the stable and zeroing time of flow significantly increase(|r|greater than 0.95),while the stable and zeroing time of rotational speed,power,and head display a smaller sensitivity on the valve opening(|r|less than 0.6).

Clinical Study of Mesenchymal Stem Cell Treatment for Acute Respiratory Distress Syndrome Induced by Epidemic Influenza A(H7N9) Infection: A Hint for COVID-19 Treatment

2013年,H7N9病毒在哺乳动物宿主之间迅速传播,并具有人与人之间传播的风险。患者表现为重症肺炎、急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS)和呼吸衰竭。间充质干细胞(mesenchymal stem cell,MSC)移植在病毒性肺炎的治疗中有广阔的前景,并于2013年作为应急性治疗方法来治疗H7N9感染的ARDS。该研究在单中心开展,为开放式临床研究。根据自愿和知情同意的原则,17例H7N9感染的ARDS患者移植同种异体经血来源的MSC作为治疗组,44例H7N9感染的ARDS患者作为对照组。与对照组相比,MSC移植显著降低了ARDS病死率(MSC治疗组和对照组死亡率分别为17.6%和54.5%)。此外,在对4名MSC移植患者进行为期5年的随访中,未发现MSC移植产生有害影响。总体而言,该研究结果表明MSC移植显著提高了H7N9感染的ARDS的存活率,并为开展临床前和临床应用MSC治疗H7N9感染的ARDS的研究提供了理论基础。由于H7N9和新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)临床表现相似(如ARDS和呼吸衰竭),并继发多器官功能障碍,因此基于MSC的疗法可能为COVID-19所致的ARDS患者获益。

A Deep Learning System to Screen Novel Coronavirus Disease 2019 Pneumonia

实时逆转录聚合酶链反应(RT-PCR)检测早期新冠病毒肺炎(COVID-19)患者的痰液或鼻咽拭子中的病毒RNA阳性率较低。同时,COVID-19的计算机断层扫描(CT)影像学的临床表现有其自身的特点,不同于甲型流感病毒性肺炎(IAVP)等其他类型的病毒性肺炎。本研究旨在应用深度学习技术,建立COVID-19、IAVP及健康人群肺部CT的早期筛查模型。本研究共采集618份CT样本,其中219份样本来自110例COVID-19患者(平均年龄50岁,其中男性63例,占57.3%),224份样本来自224例IAVP患者(平均年龄61岁,其中男性156例,占69.6%),175份样本来自健康人群(平均年龄39岁,其中男性97例,占55.4%)。所有CT样本均来自浙江省三家COVID-19定点收治医院。我们首先利用胸部CT图像集的三维(3D)深度学习模型分割出候选感染区域,然后利用位置敏感机制深度学习网络将这些分离的图像归类为COVID-19、IAVP以及与感染无关(ITI)的图像,并且输出相应置信度得分。最后,用Noisy-OR贝叶斯函数计算每份CT病例的感染类型及总置信度。测试数据集的实验结果表明,从整体CT病例来看,本研究利用深度学习系统建立的COVID-19患者的早期筛查模型的总体准确率为86.7%。该模型有望成为一线临床医生诊断COVID-19的一种有效的辅助方法。

Development of high-oil maize haploid inducer with a novel phenotyping strategy

Doubled haploid(DH) technology is important in modern maize breeding. Haploid inducers determine the efficiency of both haploid induction and identification. It has taken decades to improve the efficiency,haploid induction rate(HIR), from the ~2% of the ancestor haploid inducer, stock6, to the ~10% of modern haploid inducers. Improvement of kernel oil content(KOC) would further enhance haploid identification efficiency. Using molecular marker-assisted selection, in combine with the number of haploids per ear as phenotypic criterion, we developed a new high-oil haploid inducer line, CHOI4, with a mean HIR of 15.8%and mean KOC of 11%. High KOC of CHOI4 can achieve a mean accuracy greater than 90% in identification of haploids of different backgrounds, with reduced false discovery rates and false negative rates in comparison with the previous high-oil haploid inducer line, CHOI3. Comparison of phenotypic selection strategies suggested that the number of haploids per ear can be used as a phenotyping criterion during haploid inducer line development. CHOI4 could further increase the efficiency of large-scale DH breeding programs with lower cost.

Evaluation and Analysis of the Effect of Lignin Amelioration on Loess Collapsibility

The road subgrade and road surface in collapsible loess area are prone to many engineering diseases such as uneven subgrade settlement,insufficient bearing capacity of soaked foundation,collapse and instability of sub-grade side slope due to the special properties of loess.As an environment-friendly,low-cost soil modifier with good adhesion and chelation properties,lignin has been considered to be used in highway subgrade construction.In order to explore the effect of lignin on loess,the compressive and collapsible properties of modified loess with different lignin contents were analyzed based on consolidation compression test.The improvement mechanism of lignin on loess collapsibility was studied by means of infiltration test and SEM test.The results show that lignin fibers can promote the agglomeration of loose particles and form a network structure in the soil particle pores,enhance the cementation strength between particles and soil skeleton,and reduce the permeability of loess.With the increase of lignin fiber content,the improvement degree of loess collaps ility shows a trend of first increasing and then decreasing.When the lignin fiber content is 2%,the effect is the best,and the improved loess ollapsi-bility is eliminated.

Contingency management strategies of the Nursing Department in centralized rescue of patients with coronavirus disease 2019

Objectives:This article aims to summarize a series of contingency management strategies of the Nursing Department in the centralized treatment of patients with coronavirus disease 2019(COVID-19).Methods:The strategies of the Nursing Department included an early warning for prevention and control,taking functions of vertically commanding and horizontally coordinating,and reasonably allocating nursing workforce,to facilitate centralized treatment work in the in-hospital fever clinic,isolation wards and ICU,and referral and admission of critical patients.Five special groups were established in charge of training and examination,management and supervision,psychological support,logistical support,and reporting and publicity,respectively.Results:It was achieved that no deaths from critical patients and no medical staff,no other patients were infected.Conclusion:Through the implementation of these strategies,safe and efficient centralized treatment was ensured timely,orderly and sustainably.

Quaternary-ammonium-immobilized polystyrenes as efficient and reusable heterogeneous catalysts for synthesis of cyclic carbonate:Effects of linking chains and pendent hydroxyl group

Spherical polystyrene‐supported ammonium salts containing different linking chains between the support and ammonium groups were prepared as efficient and easily reusable heterogeneous catalysts for the cycloadditions of CO2and epoxides.The effects of the length of the linking chains and a hydroxyl group pendent on the linking chain on the catalytic performance of ionic liquid immobilized catalysts and their mechanisms were studied through experiments and density functional theory calculations.It was found that,compared with a short linking chain,a long chain can make the halogen anion more negative and provide a larger contact area of the catalysts with the reactants,thus enhancing the reaction kinetics.The hydroxyl group can stretch the C-O bonds of the epoxides,promoting the reaction thermodynamics.As a result,for the cycloaddition of propylene oxide,the yield of propylene carbonate is much higher for the catalyst with a long linking chain(yield:91.4%)compared with the yield for that with a short chain(yield:70.9%),and is further increased in the presence of pendent hydroxyl groups(yield:98.5%).The catalyst also shows a high catalytic activity even at mild temperature and good reusability(yield:≥96%for10cycles),and the selectivity is always above99%.

Surface modification of up-conversion luminescence material Na[Y_(0.57)Yb_(0.39)Er_(0.04)]F_4 with hydrosulfide group

A new method was reported for surface modification of an up-conversion luminescence material with hydrosulfide group. The factors that may influence the surface modification,such as reaction time,amount of catalyzer and modifier,and reaction solvent,were investigated. The optimal conditions were that the reaction time,the quantity of the basic catalyzer,the quantity of modifier and the volume of reaction solvent were 40 min,1.0,1.0,and 40 mL,respectively. The results indicated that hydrosulfide group content modified on the surface of up-conversion luminescence material reached to 0.1430 mmol/g,and this modified up-conversion luminescence material could be widely used in the study of structure of protein and the property of microenvironment.

Causes of Recurrence of Rice Chilo suppressalis( Walker) in Longyou County and Prevention and Control Measures

In recent years,the occurrence of rice Chilo suppressalis( Walker) in Longyou County of Zhejiang Province has increased year by year and has become aggravated. This poses a great threat to the safety of rice production. In order to curb the recurrence momentum of rice C. suppressalis,according to the dynamic monitoring and field system survey of rice C. suppressalis in Longyou County since 2015,the causes of the annual increase of rice C. suppressalis in recent years were analyzed,and the recurrence area of C. suppressalis was introduced,and finally some prevention and control measures were put forward.

Generation of Hepatitis B virus PreS2-S antigen in Hansenula polymorpha

Despite the long availability of a traditional prophylactic vaccine containing the HBV surface antigen(HBsA g) and aluminum adjuvant, nearly 10% of the population remains unable to generate an effective immune response. Previous studies have indicated that hepatitis B virus(HBV) PreS 2-S is abundant in T/B cell epitopes, which induces a stronger immune response than HBsA g, particularly in terms of cytotoxic T lymphocyte(CTL) reaction. In the current study, the HBV PreS 2-S gene encoding an extra26 amino acids(PreS 2 C-terminus) located at the N-terminus of HBsA g was cloned into the pV CH1300 expression vector. Pre S2-S expressed in the methylotrophic yeast, Hansenula polymorpha, was produced at a yield of up to 250 mg/L. Subsequent purification steps involved hydrophobic adsorption to colloidal silica, ion-exchange chromatography and density ultracentrifugation. The final product was obtained with a total yield of ~15% and purity of ~99%. In keeping with previous studies, ~22 nm viruslike particles were detected using electron microscopy. The generated PreS 2-S antigen will be further studied for efficacy and safty in animals.

Research on Detection Method of Interest Flooding Attack on Content Centric Network

To improve the attack detection capability of content centric network(CCN),we propose a detection method of interest flooding attack(IFA)making use of the feature of self-similarity of traffic and the information entropy of content name of interest packet.On the one hand,taking advantage of the characteristics of self-similarity is very sensitive to traffic changes,calculating the Hurst index of the traffic,to identify initial IFA attacks.On the other hand,according to the randomness of user requests,calculating the information entropy of content name of the interest packets,to detect the severity of the IFA attack,is.Finally,based on the above two aspects,we use the bilateral detection method based on non-parametric CUSUM algorithm to judge the possible attack behavior in CCN.The experimental results show that flooding attack detection method proposed for CCN can not only detect the attack behavior at the early stage of attack in CCN,but also is more accurate and effective than other methods.

Research on Privacy Disclosure Detection Method in Social Networks Based on Multi-Dimensional Deep Learning

In order to effectively detect the privacy that may be leaked through social networks and avoid unnecessary harm to users,this paper takes microblog as the research object to study the detection of privacy disclosure in social networks.First,we perform fast privacy leak detection on the currently published text based on the fastText model.In the case that the text to be published contains certain private information,we fully consider the aggregation effect of the private information leaked by different channels,and establish a convolution neural network model based on multi-dimensional features(MF-CNN)to detect privacy disclosure comprehensively and accurately.The experimental results show that the proposed method has a higher accuracy of privacy disclosure detection and can meet the real-time requirements of detection.

Drug target discovery by magnetic nanoparticles coupled mass spectrometry

Drug target discovery is the basis of drug screening.It elucidates the cause of disease and the mechanism of drug action,which is the essential of drug innovation.Target discovery performed in biological systems is complicated as proteins are in low abundance and endogenous compounds may interfere with drug binding.Therefore,methods to track drug-target interactions in biological matrices are urgently required.In this work,a Fe_(3)O_(4) nanoparticle-based approach was developed for drug-target screening in biofluids.A known ligand-protein complex was selected as a principle-to-proof example to validate the feasibility.After incubation in cell lysates,ligand-modified Fe_(3)O_(4) nanoparticles bound to the target protein and formed complexes that were separated from the lysates by a magnet for further analysis.The large surface-to-volume ratio of the nanoparticles provides more active sites for the modification of chemical drugs.It enhances the opportunity for ligand-protein interactions,which is beneficial for capturing target proteins,especially for those with low abundance.Additionally,a one-step magnetic separation simplifies the pre-processing of ligand-protein complexes,so it effectively reduces the endogenous interference.Therefore,the present nanoparticle-based approach has the potential to be used for drug target screening in biological systems.

A Prediction Method of Fracture Toughness of Nickel-Based Superalloys

Fracture toughness plays a vital role in damage tolerance design of materials and assessment of structural integrity.To solve these problems of com-plexity,time-consuming,and low accuracy in obtaining the fracture toughness value of nickel-based superalloys through experiments.A combination prediction model is proposed based on the principle of materials genome engineering,the fracture toughness values of nickel-based superalloys at different temperatures,and different compositions can be predicted based on the existing experimental data.First,to solve the problem of insufficient feature extraction based on manual experience,the Deep Belief Network(DBN)is used to extract features,and an attention mechanism module is introduced.To achieve the purpose of strengthen-ing the important features,an attention weight is assigned to each feature accord-ing to the importance of the feature.Then,the feature vectors obtained by the DBN module based on the Attention mechanism(A-DBN)are spliced with the original features.Thus,the prediction accuracy of the model is improved by extracting high-order combined features and low-order linear features between input and output data.Finally,the spliced feature vectors are put into the Support Vector Regression(SVR)model to further improve the regression prediction abil-ity of the model.The results of the contrast experiment show that the model can effectively improve the prediction accuracy of the fracture toughness value of nickel-based superalloys.

Diagnosis of long QT syndrome via support vector machines classification

Congenital Long QT Syndrome (LQTS) is a genetic disease and associated with significant arrhythmias and sudden cardiac death. We introduce a noninva-sive procedure in which Discrete Wavelet Trans-form (DWT) is used to extract features from elec-trocardiogram (ECG) time-series data first, then the extracted features data is classified as either abnormal or unaffected using Support Vector Machines (SVM). A total of 26 genetically identified patients with LQTS and 19 healthy controls were studied. Due to the limited number of samples, model selection was done by training 44 instances and testing it on remaining one in each run. The proposed method shows reasonably high average accuracy in LQTS diagnosis when combined with best parameter selection process in the classifica-tion stage. An accuracy of 80%is achieved when Sigmoid kernel is used in v-SVM with parameters v = 0.58 and r = 0.5. The corresponding SVM model showed a classification rate of 21/26 for LQTS pa-tients and 15/19 for controls. Since the diagnosis of LQTS can be challenging, the proposed method is promising and can be a potential tool in the correct diagnosis. The method may be improved further if larger data sets can be obtained and used.

Research on the Method of Implementing Named Data Network Interconnection Based on IP Network

In order to extend the application scope of NDN and realize the transmission of different NDNs across IP networks,a method for interconnecting NDN networks distributed in different areas with IP networks is proposed.Firstly,the NDN data resource is located by means of the DNS mechanism,and the gateway IP address of the NDN network where the data resource is located is found.Then,the transmission between different NDNs across the IP network is implemented based on the tunnel technology.In addition,in order to achieve efficient and fast NDN data forwarding,we have added a small number of NDN service nodes in the IP network,and proposed an adaptive probabilistic forwarding strategy and a link cost function-based forwarding strategy to make NDN data obtaining the cache service provided by the NDN service node as much as possible.The results of analysis and simulation experiments show that,the interconnectionmethod of NDN across IP network proposed is generally effective and feasible,and the link cost function forwarding strategy is better than the adaptive probability forwarding strategy.

A Fast Detection Method of Network Crime Based on User Portrait

In order to quickly and accurately find the implementer of the network crime,based on the user portrait technology,a rapid detection method for users with abnormal behaviors is proposed.This method needs to construct the abnormal behavior rule base on various kinds of abnormal behaviors in advance,and construct the user portrait including basic attribute tags,behavior attribute tags and abnormal behavior similarity tags for network users who have abnormal behaviors.When a network crime occurs,firstly get the corresponding tag values in all user portraits according to the category of the network crime.Then,use the Naive Bayesian method matching each user portrait,to quickly locate the most likely network criminal suspects.In the case that no suspect is found,all users are audited comprehensively through matching abnormal behavior rule base.The experimental results show that,the accuracy rate of using this method for fast detection of network crimes is 95.9%,and the audit time is shortened to 1/35 of that of the conventional behavior audit method.

Carbon uptake by cement in China:Estimation and contribution to carbon neutrality goals

Cement is a widely used construction material globally.Its manufacturing contributes to anthropogenic CO_(2)emissions significantly.However,its alkaline compounds can absorb CO_(2)from the surrounding environment and engage in a carbonation reaction,thereby functioning as a carbon sink.As a major cement producer and consumer,China has an important responsibility to rigorously investigate and accurately account for cement carbon uptake.This study presents a comprehensive analytical model of cement carbon uptake from China,revealing a substantial increase in carbon uptake from 1930 to 2021,peaking at 426.77 Mt CO_(2)(95% Confidence Interval:317.67-874.33 Mt CO_(2))in 2021.The uptake accounts for 8.10% to 45.40% of China’s annual land sink and 2.51% to 4.54% of the global land sink.The cumulative carbon uptake by cement is approximately 7.06 Gt CO_(2)(95%CI:5.22–9.44 Gt CO_(2))during this period,offsetting 50.7% of the total emissions(13.91 Gt CO_(2),95%CI:12.44–17.00 Gt CO_(2))from the cement industry.Notably,cement mortar contributed to most absorption(65.64%).From a life cycle perspective,the service stage of cement materials is the period where the largest CO_(2)sink is formed,accounting for 90.03% of the total.Therefore,the potential for carbon sequestration in cement materials and their waste is enormous.Additionally,the model improves the accuracy of cement carbon accounting,supporting both China and global carbon neutrality assessments.Thus,it is crucial for China to achieve its carbon neutrality goals sooner by prioritizing the environmental benefits of cement materials and wastes,and accelerating the development and commercialization of CO_(2)sequestration technologies for cement and its by-products.

Value of Metagenomic Next-Generation Sequencing in Clinical Diagnosis and Targeted Therapy of Nontuberculous Mycobacteria Infection

The purpose of this study was to assess the value of metagenomic next-generation sequencing(mNGS)for rapid diagnosis of diseases caused by nontuberculous mycobacteria(NTM).We retrospectively reviewed four NTM-infected cases diagnosed by smear microscopy,mycobacterial culture and mNGS methods.We found that the mNGS method not only had a shorter detection turnaround time(3–4 days)than Mycobacterium culture(15–20 days)but also had higher sensitivity and specificity to identify NTM compared with conventional detection methods.In addition,mNGS was able to identify coinfections by NTM and other bacteria,fungi or viruses.Overall,diagnosis of NTM by mNGS can provide timely and precise guidance for subsequent clinical treatment of NTM infections.

Treatment strategy for erythropoietic protoporphyria accompanied by severe abdominal pain and liver injury

To the Editor,Erythropoietic protoporphyria(EPP)is a genetic disease caused by a lack of the enzyme ferrochelatase(FECH)in the heme biosynthesis pathway due to genetic defects.FECH deficiency is caused by a deleterious FECH variant in transposition to the frequently occurring hypomorphic allele or by the presence of biallelic pathogenic variants.1 EPP could lead to abnormal production and excretion of protoporphyrin IX,2 causing clinical manifestations such as skin damage and liver injury.3–5.